Breeding plants for stress conditions
Fatemeh Bavandpouri; Ezatollah Farshadfar; Mohsen Farshadfar
Abstract
IntroductionWheat plays a key role in providing human food, providing 54% of the energy of every human being. Drought is a global problem that has placed major constraints on increasing wheat production in arid and semi-arid regions such as Iran. Among the various stresses, the most difficult to measure ...
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IntroductionWheat plays a key role in providing human food, providing 54% of the energy of every human being. Drought is a global problem that has placed major constraints on increasing wheat production in arid and semi-arid regions such as Iran. Among the various stresses, the most difficult to measure in terms of measurement is drought stress; Because different mechanisms lead to resistance. Drought stress is one of the most important factors that may be caused by low rainfall, high temperatures and high winds. The plant's reaction to it depends on the stage of growth in which the stress occurs. Different methods have been proposed for the identification and screening of drought tolerant, tolerant and drought sensitive cultivars. The most important of them include: drought Susceptibility Index, Yield Index (YI), Stress Tolerance Index (STI), Geometric Mean Productivity (GMP), Harmonic Mean (HMP), Modified Stress Tolerance Index (MSTI), Drought Resistance Index, Drought susceptible index, drought response index, non-biotic stress tolerance index, relative efficiency index (REI), Schneider stress intensity index (SSSI) and mean relative productivity (MRP). Also, the total rank has been used for better conclusions about all indicators. The aim of this study was to evaluate the drought tolerance of native bread wheats based on yield indices and integrated selection index under stress and non-stress conditions, as well as selection of water-tolerant stress-tolerant genotypes and to investigate the relationship between yield and drought resistance indices.Materials and methodsTo evaluate the drought tolerance of 25 wheat genotypes, this experiment was carried out based on a randomized complete block design with three replications under stress and non-stress conditions at Razi University of Kermanshah, Iran, from 2016 to 2017. Studied indices including: drought Susceptibility Index, Yield Index (YI), Stress Tolerance Index (STI), Geometric Mean Productivity (GMP), Harmonic Mean (HMP), Modified Stress Tolerance Index (MSTI), Drought Resistance Index, Drought susceptible index, drought response index, non-biotic stress tolerance index, relative efficiency index (REI), Schneider stress intensity index (SSSI) and mean relative productivity (MRP). All required statistical calculations including correlation coefficients, calculation of statistical indicators and parameters and drawing of biplot diagram were performed by EXCEL, SPSS and STATISTICA software.Results and discussion Significant difference between genotypes for all indices and yield in both conditions were obtained. There is a significant and positive correlation between GMP, STI, HMP, MSTI, MRP, MP YI and REI indices with yield performance in non-stress and stress environments. STS and ISI indices showed that genotypes 10(WC.4987) and 15(WC.47638) were superior. Based on the bioplat obtained from the first and second main components, genotypes 24(WC.4583), 11(WC.47615), 4(WC.47341), 22(WC,47467), 21(WC, 47640), 12(WC.4612) and 16(WC.47638) are suitable for both conditions due to their proximity to the superior indices. Priciple components analysis in stress and non-stress conditions showed that the first two components (57.21%) and the second component (41%) together explained 98.21% of the variance. Drought tolerant cultivars show different results based on one index. For example, according to STI index, genotypes 10, 18, 15 and 20 were identified as drought tolerant, but according to GMP index, genotypes 10, 18, 15 and 13 were identified as drought tolerant genotypes. Due to differences in the results, the ranking was used for more accuracy. Based on total rankings, mean rankings and standard deviation of rankings, genotypes 8, 10 and 15 had the best rankings and were known as drought tolerant genotypes and genotypes 4, 11 and 22 as susceptible genotypes. As a result, these genotypes can be used for crossbreeding and genetic analysis for resistance, through various methods such as diallel analysis, mapping, marker selection, and so on.ConclusionsThe rate of yield reduction due to stress varies in different genotypes. Tolerant genotypes have the lowest yield loss and susceptible genotypes have the highest yield loss. The correlation between drought resistance and yield indices under stress and non-stress conditions showed that MP, STI, GMP, HMP, MSTI, YI, MRP and REI indices are suitable for selecting high yield genotypes under two conditions. According to the three-dimensional biplot, genotypes 10, 15 and 18 were superior in stress and non-stress conditions. According to STS and ISI indices, genotypes 8, 10 and 15 were more tolerant. Using one or a small number of indices to select drought tolerant cultivars will have different results, so ranking was used; In ranking based on total rankings, mean rankings and standard deviation of rankings, genotypes 8, 10 and 15 had the best rankings and were known as drought tolerant genotypes and genotypes 4, 11 and 22 as susceptible genotypes. . For more accurate results, these experiments should be repeated for more years so that these genotypes can be used as promising lines to increase production yield.
Drought stress
Roghaieh Khojamli; Khalil Zaynali Nezhad; Ali Asghar Nasrollahnejad Ghomi; Saeed Bagherikia
Abstract
IntroductionThe existence of drought stress at the beginning of the growing season is one of the most important threatening factors in wheat production of Iran. The coleoptile length is the most important morphological trait in determining sowing depth, emergence power and seedling establishment. The ...
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IntroductionThe existence of drought stress at the beginning of the growing season is one of the most important threatening factors in wheat production of Iran. The coleoptile length is the most important morphological trait in determining sowing depth, emergence power and seedling establishment. The coleoptile length has been used as an effective indicator for selecting the drought tolerant genotypes in wheat breeding programs. Various indices have been developed to evaluate crop response to various stresses, including tolerance index (TOL), productivity mean (MP), geometric mean productivity (GMP), harmonic mean (HM), stress tolerance index (STI), stress sensitivity index (SSI), yield index (YI), yield stability index (YSI) and relative stress index (RSI). The efficiency of each indices depends on the breeding objectives and the target environment.Materials and methodsIn order to evaluate some of the landrace wheat genotypes under drought stress conditions at the seedling stage, an experiment with 35 pure lines under three moisture conditions (control, drought stress with PEG6000 10% and 15%) was conducted in a completely randomized design (CRD) with three replications at Gorgan university of agricultural sciences and natural resources.. The coleoptile length was measured after eight days. The indices of MP, GMP, HM, STI, SSI, YI, TOL, RSI and YSI were calculated based on the coleoptile length values under control (Yp) and stress (Ys) conditions. Data analysis was performed using iPASTIC: an online toolkit to estimate plant abiotic stress indices.Results and discussionIn control and 10%-drought stress conditions, genotypes 11 and 2 had the highest of coleoptile length. While, in 15%-drought stress conditions, genotypes 3 and 6 had the highest of coleoptile length, respectively. Also in control and 15%-drought conditions genotypes 30 and 35 and in 10%-drought stress conditions genotypes 15 and 21 had the lowest of coleoptile length. Based on MP, GMP, HM, STI and YI indices, genotypes 2 and 11 were identified as tolerant genotypes, while genotypes 15, 21 and 30 were susceptible genotypes, under 10% drought stress conditions. Under 15%-drought stress conditions, MP, GMP, HM, STI and YI indices identified genotypes 21 and 34 as the most susceptible genotypes, whereas genotypes 30 and 35 were the most susceptible genotypes. Under three moisture conditions, the coleoptile length had the highest coefficient of correlation (positive and significant) with MP, GMP, HM and STI indices. Using three-dimensional plots, the genotypes were divided into four groups A, B, C, and D. The most appropriate indices being the ability to distinguish group A, from other groups. Group A selects genotypes that have high yield in both control and stress conditions. The result showed genotypes 3, 6, 11, 16, 19, 20 and 24 were classified as group A in both drought stress conditions. The Iranian commercial cultivars (genotypes 30, 34 and 35) placed in Group D, which indicates insufficient attention to drought stress at the seedling stage, while tolerance to terminal drought stress is one of the most important goals in wheat breeding programs of Iran. Principal component analysis (PCA) showed that the first two PCAs explained 99.78% of the variation in 10%-drought stress and 99.80% in 15%-drought stress conditions. MP, GMP, HM and STI had the sharp angles with together that it indicates high correlation among mentioned indices. Multivariate biplos showed that drought tolerant genotypes were adjacent to vectors related to the best drought tolerance indices.ConclusionsCorrelation coefficients of drought tolerance indices showed that MP, GMP, HM and STI were the most suitable indices for selecting of drought tolerant genotypes. Based on stress tolerance indices and 3D plots, genotypes 3, 6, 11 and 24 (originated from Turkey, Afghanistan, Iran and Afghanistan, respectively) were identified as drought tolerant genotypes at the seedling stage, while genotypes 14, 15, 21, 30 and 35 were identified as the most susceptible genotypes. The landrace genotypes identified in this study could be used in breeding programs of bread wheat under drought stress at the seedling stage.
Drought stress
Seyed Ehsan Sangi; Abdollah Najaphy; Kianoosh Cheghamirza; Reza Mohammadi
Abstract
IntroductionDurum wheat (Triticum durum L.) is grown on 10% of the world’s wheat area. In spite of its low acreage, durum wheat is an economically important crop because of its unique characteristics and end products. Drought stress is one of the most devastating environmental stresses that depresses ...
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IntroductionDurum wheat (Triticum durum L.) is grown on 10% of the world’s wheat area. In spite of its low acreage, durum wheat is an economically important crop because of its unique characteristics and end products. Drought stress is one of the most devastating environmental stresses that depresses wheat yield productivity in many parts of the world. Breeding for drought tolerance is critical for sustainable wheat production in these areas. Different indices, including tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), stress susceptibility index (SSI), harmonic mean (HAM), yield index (YI), and yield stability index (YSI) have been employed for screening the stress tolerant genotypes. The objectives of the study were to assess durum wheat genotypes under stress and non-stress conditions and to evaluate drought resistance indices in identifying genotypes adapted to the conditions.Materials and methodsThe experiment was carried out at the research farm of Faculty of Agriculture, Razi University, Kermanshah, during 2015-2016 cropping season. In this study, 23 durum wheat genotypes originally from Iran and ICARDA were evaluated using a randomized complete block design with three replications under stress (rain-fed) and non-stress (irrigated) conditions. Irrigated plots were watered three times at flowering and grain filling stages. Rain-fed plots received no water other than rainfall. Grain yield (g/m2) was measured. Tolerance indices were calculated for genotypes based on the grain yield. Combined analysis of variance appropriate to RCBD was carried out using SAS. Environments (rain-fed and irrigated) were considered as fixed effects. Least significant difference (LSD) test was used for the mean comparisons. Orthogonal comparisons and correlation analysis were performed by SAS software. Principal component analysis (PCA) and biplot diagram were carried out by MINITAB 17 and Stat graphics 18.1.01, respectively.Results and discussionThe results of combined analysis of variance showed significant differences between environments (rain-fed and irrigated) and genotypes for grain yield. Orthogonal comparisons showed that there was a significant difference between Iranian genotypes (contrast 1) in both conditions. Also, there were significant differences between ICARDA genotypes (contrast 2) and Iranian and ICARDA genotypes (contrast 3). Results showed that water stress reduced the grain yield of all genotypes and mean grain yield in rain-fed conditions was 32% lower than that in irrigated conditions (the stress intensity was 0.32). Based on all calculated drought indices, in most cases genotypes 15, 10, 18, 12 and 19 were tolerant and genotypes 2, 9, 17, 4 and 7 were susceptible to drought stress. The results of correlation analysis showed that TOL, MP, GMP, STI, YI and HAM had significant (P≤0.01) and positive correlations with grain yield under non-stressed condition. The MP, GMP, STI, YI and HAM revealed a significant (P≤0.01) and positive correlations with yield under stressed condition. Positive and significant correlation were observed between Ys and Yp and also with MP, GMP, STI, YI and HAM indicated that these indices are the most suitable indices to screen genotypes in drought stress conditions. Principal component analysis showed that the first component explained 71% of the variation with Ys, Yp, MP, YI, GMP, STI and HAM. First dimension can be considered as the yield in both environments and drought tolerance. Second component explained 28% of the total obtained variation and can be named drought susceptible dimension. Hence, selection of genotypes with high PCA1 and low PCA2 are suitable for both stress and non-stress environments. Thus, Genotypes 18, 22 and 23 with rather higher PCA1 and lower PCA2 are superior genotypes under both stressed and non-stressed conditions (Group A). Genotypes 19, 14, 3, 16, 21 and 20 could be known as Group B. These genotypes are suitable for non-stressed conditions. Genotypes 4, 7, 17 and 13 are drought susceptible and had low yield in both conditions (Group D). Genotypes 15, 10, 12, 11 and 6 with high amount of yield stability index (YSI) had a relatively low yield in both conditions, but they were more stable genotypes than the others (Group C).ConclusionWhat can be concluded from these results are: 1) Identifying the genotypes with high and stable yield in both conditions which are 18, 22 and 23 originated from ICARDA.2) Identifying genotypes with low yield in both conditions and susceptible to drought which are 4, 7, 17 and 13.3) Suggesting genotypes 19, 14, 3, 16, 21 and 20 for non-stress conditions.
Drought stress
Seyyed Mohammad Taghi Tabatabai
Abstract
IntroductionBread wheat is one of the grains in the world that provides 20% of the plant-derived protein to the people of the world (Acevedo et al., 2002; Godfray et al., 2010). Drought is an important environmental factor limiting the production of wheat and other crops in the world. Water scarcity ...
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IntroductionBread wheat is one of the grains in the world that provides 20% of the plant-derived protein to the people of the world (Acevedo et al., 2002; Godfray et al., 2010). Drought is an important environmental factor limiting the production of wheat and other crops in the world. Water scarcity has made the production of higher drought-tolerant cultivars an important goal in many breeding programs. One of the goals of wheat cultivation in arid and semi-arid regions is to achieve cultivars that are more tolerant of drought stress at the end of the season in conditions of water restriction and lack of irrigation and have less yield reduction. By achieving such figures, it is possible to increase the efficiency of operations in those conditions and to a large extent prevent the waste of water resources. The aim of this study was to identify agricultural traits associated with changes in wheat grain yield under drought stress and drought-tolerant lines. Materials and methodsIn this study, 111 lines along with 3 cultivars of Shahid Narin, Barzegar, and Sistan in the form of repeated experiments (Agent) in 1396 in the research farm of the Research Center located in Yazd city (at 15 degrees and 53 minutes to 40 degrees And 54 minutes east longitude and 46 degrees and 31 minutes to 15 degrees and 32 minutes north latitude and altitude 1200 meters). In order to check the production capacity of the lines, the control was repeated at intervals of every 20 lines. Each line was planted in 2 lines of 2.5 m with a planting distance of 20 cm. In order to investigate the effect of drought stress at the end of the season on the relevant traits in the post-flowering stage, irrigation was stopped. During the growing season, grain yield, yield, and morphological components were evaluated and compared with control cultivars. A simple correlation was used to obtain the relationship between the traits. To identify the main variables that affect grain yield, multi-variable analysis was used by stepwise regression analysis. Results and discussionThe experimental results showed that there is a great variety among the studied lines. Regression tests showed that traits such as 1000-grain weight, number of days to ripening, spike length, plant height, and spike weight had a positive and significant effect on grain yield and explained a significant share of yield changes. The classification of lines is based on cluster analysis by the UPGMA method in 9 groups. Based on the obtained results, 15 genotypes were selected that had more grain yield and some more suitable agricultural characteristics than other genotypes and cultivars. ConclusionAlthough drought stress affects most plant growth traits, this effect depends on the time the plant is exposed to water stress and the lines being tested. The results of this study show that water stress has a different effect on the growth of wheat lines and shows that the ability of bread wheat lines to tolerate drought stress is different. Also, the genetic material in this experiment could be a valuable resource that, in addition to removing new traits, provides a great variety for breeders to improve and produce drought-tolerant wheat cultivars.
Drought stress
Alireza Ahrar; farzad paknejad; Seyed Ali Tabatabaei; Fayaz Aghayari; Elias Soltani
Abstract
IntroductionOne of the crops that are considered as new sources of human nutrition as well as animal feed and poultry is the Amaranth. The leaves of most of the Amaranth species are used orally for human or animals use worldwide. According to the patterns of drought, irrigation management plays an important ...
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IntroductionOne of the crops that are considered as new sources of human nutrition as well as animal feed and poultry is the Amaranth. The leaves of most of the Amaranth species are used orally for human or animals use worldwide. According to the patterns of drought, irrigation management plays an important role in improving or enhancing crop yields, especially in arid and semi-arid regions. In this regard, identification of indices for tolerance and susceptibility to drought stress has always been of interest to researchers and it can be very effective. Many scientists have tried to find the best index for stress tolerance in plants. This study aimed to evaluate the best indices for determination of drought tolerance in forage Amaranth cultivars.Materials and methodsExperimental research farm with a geographical position of 31 degrees 54 minutes north and 54 degrees 16 minutes west of 1215 meters above sea level is located in Yazd province. The tested cultivars were planted in plots of 40 m2 in two consecutive years (May 2018-19). The planting was done in a row, and immediately the first irrigation was done. Fertilization was done every two years according to soil analysis and plant requirement. Split-plot experiment based on a completely randomized block design with three replications was used for this study. The main factor, including four levels of water-deficit for the plant (50, 60, 70 and 80%) was considered. And Cim and Kharkovski, who all belong to the Amaranthus hypochondriacus family, constituted the sub-factor of the test. Parameters such as yield, agricultural water productivity, leaf-to-stem weight ratio, stem diameter, plant height and crude protein percentage were investigated. Then, using dry forage yield of the Amaranth, famous indices were used to calculate resistance and stability of drought stress. In this essay, SAS 9.4 software was used for data analysis of variance and Statgraphics 18 software was applied for drawing graphs and principal components analysis.Results and discussionCombine analysis was performed for two years on all traits. Interaction effects revealed that with increasing drought stress, fresh forage yield in Amaranth cultivars was significantly reduced, as Loura and Cim had the highest yield at 50% water depletion conditions, while Loura and Kharkovski cultivars at 80% of water discharge showed the lowest yield. Agricultural water productivity also yielded similar results. The ratio of leaf to stem weight in the interaction of treatments had no significant difference. But the diameter and height of stems decreased significantly with increasing drought stress levels in all cultivars, but this decrease was more pronounced in Kharkovski. Subsequently, the principal component analysis was performed to evaluate the genotypes. It was found that the Cim cultivar is the most resistant to high levels of drought stress. ConclusionsThe results showed that with increasing drought stress levels, fodder yield significantly decreased in different cultivars. But despite the decrease in the yield, it seems that due to the quality of the forage, the relatively favourable production volume per hectare and due to the short growing season of the plant, it can be a desirable option even in low water areas. Since one of the objectives of this research was to select the optimal stress index for selection of superior cultivar for drought tolerance, by analyzing the principal component, we found that the Hm and MP indices with the yield under stress and non-stress conditions were the most valuable. However, while the Loura genotype had a higher yield under non-stress and even mild drought conditions, the Cim cultivar showed significantly better yield under drought stress. And in terms of indices, Kharkovski could never perform better than Cim.
Drought stress
Layegh Moradi; Adel Siosemardeh; Yousef Sohrabi; Bahman Bahramnejad; Farzad Hosseinpanahi
Abstract
IntroductionWheat (Triticum aestivum L.) is one of the most important grain products in the world which is the main food of the people in many parts of the world and provides about 20% of the calories needed by the world population. The late stages of wheat growth in the Mediterranean regions are usually ...
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IntroductionWheat (Triticum aestivum L.) is one of the most important grain products in the world which is the main food of the people in many parts of the world and provides about 20% of the calories needed by the world population. The late stages of wheat growth in the Mediterranean regions are usually accompanied by drought stress. Supplemental irrigation is one of the appropriate strategies to reduce the damaging effects of drought stress and improve yield and sustainability. Nitrogen is the most important nutrient in rainfed farming after wheat planting is the most important tool available to increase yield. Nitrogen fertilizer application to soil at late vegetative stage may not be appropriate due to dry soil surface and reduced root activity, Therefore Nitrogen spraying can be used as a quick and efficient way to meet plant nutrition due to its advantages such as faster and more uptake by the plant. Matherial and methodIn order to study the effect of supplemental irrigation and different rates of urea fertilizer and urea foliar application on dry matter remobilization, yield and yield components and Grain protein contents experimental wheat in split –split plot in randomized complete block design with three replications It was designed and implemented in the research farm of Kurdistan University in 2016-2017. Treatments included irrigation levels (no irrigation and irrigation at booting stage) as main factor, three dry wheat cultivars (Rejaw, Sardari and Azar 2) as sub factor of different rates of nitrogen fertilizer (50 kg urea in fall (A), A + 50 kg urea in the spring (B) and B + foliar solution (20 kg urea in the booting stage) were used as a sub-factor. The studied traits included leaf dry matter, stem + leaf pod and spike in flowering and ripening stages, leaf dry matter remobilization, stem + leaf pod and panicle seed, total soil remobilized dry matter, soil yield. Dry leaf remobilization, stem + leaf pod and pod straw, total remobilization efficiency, remobilization share in grain yield, spike number per square meter, spike number per grain, 1000-grain weight, biological yield, yield, harvest index and grain protein content.Leaf dry matter, stem + Sheath dry matter and spike dry matter in flowering and maturity stages, leaf dry matter remobilization, stem + Sheath dry matter, Chaff dry matter, total dry matter remobilized, leaf,, stem + sheath, chaff and total dry matter remobilization efficiency, remobilization share in grain yield, spike number per square meter, kernals per spike, 1000-grain weight, biological yield, yield, harvest index and grain protein content were measured. ResultsResults showed that the amount of stem + sheath, dry matter at flowering and maturity, leaf, stem + sheath, spike remobilization dry matter, total remobilization, stem+ sheath remobilization efficiency, remobilization share in grain yield, weight Spike, kernals per spike, 1000-grain weight, yield and biological yield were affected by supplemental irrigation.Among cultivars in terms of stem + sheath and chaff dry matter at flowering and maturity, leaf, stem + Sheath, spike remobilized dry matter, total remobilization, leaf remobilization efficiency, remobilization share in grain yield, weight Spike, kernals per spike, 1000-grain weight, yield, biological yield, harvest index and grain protein were different. Rejaw cultivar had more grain number per spike and yield than Azar2 and Sardari.Different rates of nitrogen fertilizer had a significant effect on stem + sheath, spike and total dry matter remobilization efficiency and remobilization share on grain yield.Supplemental irrigation at the booting stage increased dry matter stored in stem + sheath and increased the amount of remobilized dry matter during grain filling.Irrigation at booting stage increased grain yield by 12.4%. Increasing urea fertilizer and urea foliar application at the end of growth stages increased plant yield and grain quality by providing more nitrogen and stay-green.
Drought stress
Massoumeh Mohammadpur; Ali Nasroallahzadeh Asl; Mohsen Roshdi; Farzad Jalili
Abstract
IntroductionPulses are rich in protein and are an important source of human food after cereals (Ganjabadi et al., 2014). Beans are one of the most important pulses and about 49% of the pulses consumed in the world are supplied through beans (Broughton et al., 2013). Drought stress is an important factor ...
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IntroductionPulses are rich in protein and are an important source of human food after cereals (Ganjabadi et al., 2014). Beans are one of the most important pulses and about 49% of the pulses consumed in the world are supplied through beans (Broughton et al., 2013). Drought stress is an important factor that reduces yield in plant (Liu et al., 2005). Many parts of the world have water scarcity that is a limiting factor for higher yields (Safavi Ghardini et al., 2017). Plans must be adopted to increase water use efficiency. by using materials such as superabsorbent polymers, it can increase water use efficiency. Superabsorbents can absorb large amounts of water (Alahdadi, 2002). Paula et al. (2007) reported that increasing soil moisture increases the plant height of chickpeas and beans. Elami et al. (2011) stated that superabsorbent increased chlorophyll under stress conditions. adequate amount of potassium sulfate fertilizer in the soil facilitates osmotic modification in the soil, as a result of which the osmotic pressure remains in the leaves and thus increases the plant's ability to withstand drought stress. Potassium plays an important role in reducing the effects of drought stress in plants (Molodi, 2015). Fanaei et al. (2010) reported an increase in chlorophyll pigment content in rapeseed with the use of potassium during drought stress, and also stated that the amount of chlorophyll increased with the application of potassium. The aim of this experiment was to investigate the strategies for reducing drought stress damage and also saving water consumption by using superabsorbent polymer, mycorrhizal mycorrhizal fungi, nano-potassium fertilizer and seed pretreatment with hydrogen peroxide.Materials and methodsIn order to effects of irrigation disruption and drought tolerance methods on physiological characteristics and yield of pinto bean, an experiment was conducted as split plot based on randomized complete block design with three replications in Salmas city, northwest of Iran, during spring of 2018. The main plot was irrigation disruption at 3 levels (normal irrigation, irrigation disruption at the end of flowering stage, irrigation disruption at the end of poding stage) and drought resistance as the sub-factor in five levels including (control, use of superabsorbent, use of mycorrhizal fungi, use of nano-potassium fertilizer and seed priming with hydrogen peroxide) was considered. ResultsThe highest amount of total chlorophyll was related to normal irrigation treatment and the lowest amount was related to stop irrigation treatment at flowering stage. The highest total chlorophyll was related to superabsorbent polymer treatment and the lowest amount was related to control treatment. the decrease in chlorophyll concentration in plants under drought stress may be due to the decomposition of chlorophyll by increasing the activity of chlorophylase (Goldani, 2012). The highest proline concentration was related to the experimental treatment of stop irrigation in stage of flowering and control and also the lowest amount of proline was observed in normal irrigation treatment along with superabsorbent consumption. The highest grain yield was related to normal irrigation interaction treatment along with superabsorbent polymer and the lowest amount was related to irrigation stop interaction treatment in the flowering stage along with control treatment. Alhiari et al (2013) by examining the effect of superabsorbent application on yield and yield components of chickpea under drought conditions observed that superabsorbent had a significant effect on yield of chickpea plant.Conclusionas respects, the highest grain yield in the normal irrigation experimental treatment was associated with the use of superabsorbent polymer, but according to other experimental treatments, it was observed that the grain yield in the experimental treatment of irrigation cut-off from the end of the poding stage with superabsorbent consumption was almost the same with the experimental treatment of normal irrigation. it should be included in a statistical group, which can play a significant role in saving water consumption, and also by using superabsorbent, drought stress damage can be significantly reduced.
Drought stress
Majid Ghanbari; Ali Mokhtassi-Bidgoli; Kamran Mansour Ghanaei-Pashaki; Parniyan Talebi-Siah Saran
Abstract
IntroductionMaize (Zea mays L.) is widely spread all over the world due to its many characteristics, especially its ability to adapt to different climatic conditions and occupies the third position after wheat and rice in terms of crop area. Currently, maize is cultivated in more than 240 hectares of ...
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IntroductionMaize (Zea mays L.) is widely spread all over the world due to its many characteristics, especially its ability to adapt to different climatic conditions and occupies the third position after wheat and rice in terms of crop area. Currently, maize is cultivated in more than 240 hectares of Iranian land (Gheţe et al., 2018). Super Sweet Corn is a monocotyledonous, annual, single plant of the family poaceae, which is widely used in agriculture and industry (Gheţe et al., 2018). Abiotic stresses affect different aspects of plant growth, such as reduction and delay in germination, decrease in development rate, decrease in plant organs growth, and decrease in plant life duration and finally decrease in dry matter production. Among abiotic stresses, drought stress is considered to be the most influential type of stress in the production of oil seeds in the world and can greatly reduce production on many arable lands. One of the primary effects of drought is the reduction of water content of plant tissues (Ghanbari et al., 2016). Nitrogen is one of the major nutrients in biomass determination and crop yield through impact on leaf area index (radiation intake) and photosynthetic capacity per leaf area unit (Compelo et al., 2019). Potassium in physiological applications including: carbohydrate metabolism or starch formation; protein metabolism; control and regulation of various essential minerals activities; Stomach and water play a key role (Tisdale et al. 2003). This study was carried out to investigate the effect of urea fertilizers combination with solopotass fertilizers on yield and yield components of Super Sweet Corn in different irrigation regimes.Materials and methodsThis research was carried out as a factorial experiment in a randomized complete block design with three replications in Varamin Agricultural & Livestock Complex in 2016. Factorial combinations of three treatments of water deficit stress (15% (un-stressed control), 30% (moderate stress) and 45% (severe stress) of FC depletion), four nitrogen fertilizer rate (zero (un-fertilized control), 150, 200 and 250 kg.ha-1) from urea and four potassium fertilizer rate (zero (un-fertilized control), 100, 150 and 200 kg.ha-1) from potassium sulfate were considered. Drip irrigation (T-tape) was applied the row length in each experimental plot was 6 m, 50 cm apart. The distance between the plots and between the repetitions was 1 and 3.5 m, respectively. Plant to plant distance within each row was 8 cm. The irrigation schedules were based on soil moisture discharge of field capacity at the root zone of Super Sweet Corn with a depth of about 30 cm.ResultsThe results of this study showed that three-way interaction of irrigation time and chemical fertilizers was significant in leaf length and diameter, grain number, 1000 grain weight, photosynthesis rate and catalase enzyme. In moderate stress conditions, the highest grain yield was obtained from 150 kg urea and 200 kg solopotass, respectively. The highest photosynthesis rate and catalase activity were observed in the control treatment under severe stress conditions.ConclusionIn general, it can be concluded that application of 150 kg urea and 200 kg solopotass increased 37.89 % grain yield compared to control under moderate stress conditions, respectively, that indicates the ability of chemical fertilizers to increase yield and yield components as well as increase photosynthesis rate under stress conditions and is highly effective in the emergence of resistance to super sweet maize plant and severe yield loss. Finally, application of 150 kg urea and 200 kg solopotass on the moderate stress conditions is recommended for optimum yield.
Drought stress
Mohsen Shokhmgar; Mohammadjavad Seghatoleslami; Seyyed Gholamreza Mousavi; Reza Baradaran
Abstract
Introduction Abiotic stresses are major constraints for many crop plants in specific areas over the globe which limits crop production. Drought, the occurrence of a substantial water deficit in the soil, is an alarming constraint to crop productivity and yield stability worldwide. Drought is the leading ...
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Introduction Abiotic stresses are major constraints for many crop plants in specific areas over the globe which limits crop production. Drought, the occurrence of a substantial water deficit in the soil, is an alarming constraint to crop productivity and yield stability worldwide. Drought is the leading environmental stress in world agriculture, causing losses in crop yield. Drought stress adversely affects a variety of vital physiological and biochemical processes in plants, leading to reduced growth and final crop yield. One quick strategy to promote plant drought tolerance is exogenous application of various compounds, including organic solutes (organic osmolytes and plant growth regulators) and mineral nutrients. Recently, this strategy has gained considerable attention because of its efficiency, feasibility, and cost- and labor-effectiveness. In this experiment, we studied the roles of some plant growth regulators foliar application including putrescine, humic acid, salisylic acid and methanol, in foxtail millet response to drought stress in enhancing millet drought tolerance and alleviating the damaging effects of drought stress. Materials and methods In order to evaluate the effect of plant growth regulators on yield and morpho-phenological traits of foxtail millet under drought stress condition an experiment in split plot arranged in randomized complete block design with three replications conducted in two years of 2017 and 2018 at the Agricultural Research Center of Birjand branch, Islamic Azad University, Birjand. Experimental factors included drought stress as main factor in three levels (irrigation in 30, 70 and 100 percent of plant water requirement) and foliar application of plant growth regulators as sub plot in five levels (control and foliar application of putrescine, humic acid, salisylic acid and methanol). The water requirement was determined by FAO method using evaporation data from Class A pan with 80% efficiency for field water distribution (Hellen et al., 1998). In this method, FAO guidelines were used to determine the vegetative coefficient at different stages of growth. Foliar application of 1 mM salicylic acid, 1 mM putrescine, 1.5 kg.ha-1 humic acid, and 25% volumetric methanol were used in two stages (early stem elongation and early flowering). The averages of data statistically analyzed using analysis of variance (ANOVA) by using the SAS system for windows, version 9.1 (SAS Inst., 2001) and means were compared using Duncan Multiple Range Test at 0.05% probability. Results and discussion Results showed that drought stress led to significant reduction in plant height, peduncle length, number of panicle per meter square, number of grain per panicle, 1000 grain weight, grain yield and biomass while foliar application of plant growth regulators improved morphological traits, yield components and finally grain yield. The highest biomass and grain yield were obtained at 100% water requirement with 704.5 and 267.7 g.m-2, respectively. At 70% of water requirement these traits decreased by 20.2 and 25.2 percent and in 30% of water requirement they reduced by 51.2% and 58.4%, respectively. Foliar application of putrescine, humic acid, salisylic acid and methanol enhanced millet grain yield by 8.3, 23.9, 17.1 and 19.6 percent, respectively in contrast to control treatment. Investigation the interaction of year in irrigation on biomass and grain yield revealed that in both studied years, the highest values of these traits were obtained from 100% water requirement treatment and with increasing of stress intensity they reduced significantly. Conclusions Generally, results revealed that application of plant growth regulators improved foxtail millet grain yield under water stress. Application of humic acid under optimal irrigation condition and application of methanol in severe drought stress had the highest impact in improving grain yield.
Drought stress
Ashkan Asgari; Parviz Rezvani Moghaddam; Alireza Koocheki
Abstract
IntroductionPhysalis alkekengi is a well-known medicinal plant in Europe and Asia and especially in the northeastern of China. It is an economically valuable plant that can tolerate drought, waterlogging, and warm and cold temperatures. All parts of P. alkekengi could be used as medicine. P. alkekengi ...
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IntroductionPhysalis alkekengi is a well-known medicinal plant in Europe and Asia and especially in the northeastern of China. It is an economically valuable plant that can tolerate drought, waterlogging, and warm and cold temperatures. All parts of P. alkekengi could be used as medicine. P. alkekengi is a rich source of complex antioxidants, which has been suggested for the treatment of several diseases such as inflammation and rheumatism. The availability of water is the primary constraint on food production in arid and semi-arid regions. Trends of water availability indicated that agricultural activities are approaching a “water crisis” in the Middle East and North Africa. In Iran, water is a scarce resource due to the high variability of rainfall. Water stress effects on growth and yield are species is well known. Optimizing irrigation management, together with the appropriate crops, is suitable in these regions. So the aims of this study were to the effect of different irrigation levels and manure amount on yield, yield components, and fruit quality of Physalis alkekengi. Material and methodsIn order to investigate the effects of irrigation and animal manure levels on yield and yield components of Chinese lantern (Physalis alkekengi L.), a split-plot experiment was conducted based on randomized complete block design with three replications at the research field of the faculty of agriculture, Ferdowsi University of Mashhad, Iran at 2016. The experimental treatments were all combination of irrigation levels (60, 80 and 100 percent of water requirement) and four levels of animal manure (0, 10, 20 and 30 t. ha-1). Final seed yield and yield components were measured from 1 m of each plot. Characters consisted of weight of fruit per plant, number of fruit per plant, fruit weight, number of seed per fruit, 1000 seed weight, plant height, alkaloid, biological yield, and fruit yield.Data from the experiment were analyzed statistically using SAS software (Ver. 9.2). Least significant difference (LSD) test were also performed for the comparison of means. The critical difference at P = 0.05 was used to test the difference between means of individual treatments.Result and discussion Our results indicated that, irrigation levels had a significant effect on all studied traits except fruit number and single fruit weight. Also, the impact of animal manure was significant on all characteristics, except 1000 seed weight. The interactions between irrigation and animal manure were significant on fruit yield, biological yield, harvest index, and fruit weight per plant. The highest fruit weight per plant (101 and 102 gr respectively) and fruit yield (8 and 8.2 t.ha-1 respectively) were observed in 100 percent water requirement with use of 20 and 30 t.ha-1 animal manure. The highest alkaloid percent was observed in 80 percent water requirement (0.4 percent) and 30 t.ha-1 animal manure level (0.37 percent). ConclusionsBased on the results of this study, irrigation levels and manure levels had a significant effect on measured traits. The best of results was observed in irrigation of 80 % and 100 % of water requirement. On the other hand, the application of manure, especially 20 and 30 t.ha-1, improved the studied traits compared to 0 and 10 ton. According to the results of this research and considering the optimal use of resources, the most suitable method for the planting of this plant was considered by using 80 percent water requirement and 20 t.ha-1 animal manure.
Drought stress
Mohammad Ali Fazli; Touraj Mir Mahmoodi; Amir Rahimi; Saman Yazdan Seta
Abstract
IntroductionBalango (Lallemantia royleana Benth) is a medicinal and annual plant of the mint family that contains essential oils and mucilage. The most important feature of Balango plant is its seeds. These seeds are an appropriate source of fiber, oil, and protein and have nutritional and health benefits ...
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IntroductionBalango (Lallemantia royleana Benth) is a medicinal and annual plant of the mint family that contains essential oils and mucilage. The most important feature of Balango plant is its seeds. These seeds are an appropriate source of fiber, oil, and protein and have nutritional and health benefits for humans. Drought stress is one of the most important limitations of agricultural productions in arid and semi-arid regions including Iran. Recently, the impact of chemical farming and the negative consequences on the environment and human health are on the rise in Iran. Organic farming is gaining attention and increasing globally because it is eco-friendly, safe and has benefits for human health. The use of organic fertilizers in agriculture improves soil structure. The purpose of this research was to investigate the effect of irrigation and fertilizer treatments on morphophysiological characteristics of Balangu, Materials and methodsIn order to study the effect of irrigation regimes and fertilizer treatments on morphophysiological characteristics of Balangu, an experiment was conducted in a split-plot design with a randomized complete block design with three replications in the 2018 crop season. Experimental treatments included irrigation regimes at three levels (no irrigation, water deficit (supplemental) and normal) and fertilizer treatments including control, NPK, humic acid, Vermicompost, and manure. In this study, plant height, leaf area index, number of seeds per plant, 1000-grain weight, biological yield, grain yield, essential percent and essential yield, oil percent and oil yield mucilage percentage and mucilage yield were measured. After collecting the data, the data were analyzed using SAS software version 9.1 and the comparison of the average of the studied characteristics was performed using Duncan's test at the probability level of five percent. ResultsThe results showed that the effect of irrigation regimes on plant height, leaf area index, number of seeds per plant, biological yield, grain yield, essential yield, oil yield, and mucilage yield were significant. Also the difference between fertilizer treatments on plant height, leaf area index, the number of seeds per plant, biological yield, grain yield, essential percent and essential yield, oil percent and oil yield, mucilage percentage, and mucilage yield. Furthermore, the effect of irrigation interval and fertilizer treatment interaction was significant only on 1000 grain yield. The highest plant height (70.29 cm), leaf area index (3.07), number of seeds per plant (168.72), biological yield (6712 Kg/h), grain yield (2297.7 Kg/h), essential yield (2.82 Kg/h), oil yield (497.16 Kg/h), and mucilage yield (295.74 Kg/h) were assigned to complete irrigation treatment. Among fertilizer treatments, the highest plant height (71.97 cm), leaf area index (3.67), the number of seeds per plant (158.06), biological yield (6063.3 Kg/h), grain yield (2086.3a), essential percent (0.12 percent) and essential yield (2.85), oil percent (21.11 percent) and oil yield (450.60a), mucilage percentage (12.48 percent), and mucilage yield (268.41a) were assigned to Vermicompost treatment. Also, the highest 1000-grain weight (5.38 g) was allocated to supplemental irrigation and vermicompost fertilizer treatment. Therefore, complete irrigation and application of compost organic fertilizer are recommended for achieving desirable characteristics of a Balangu. ConclusionResults showed that the highest biological yield, grain yield, essential percent and essential yield, oil percent and oil yield, mucilage percentage, and mucilage yield was recorded for complete irrigation regime, Therefore, in order to achieve the maximum quantitative and qualitative characteristics of Balango, additional irrigation is recommended. In the present study the highest biological yield, grain yield, essential percent and essential yield, oil percent and oil yield, mucilage percentage, and mucilage yield has belonged to Use of vermicompost, and this treatment was able to have a significant advantage over chemical fertilizers, so by replacing vermicompost with chemical fertilizer, in addition to economic savings, it took a step towards sustainable agriculture.
Drought stress
Mojtaba Salahiostad; Bahram Abedy; Yahya Selahvarzi
Abstract
IntroductionToday, in order to prevent the destruction of water, soil and environment resources, and at the same time to achieve the desired performance in agriculture, in the conditions of environmental tensions such as drought, the use of biofertilizers is a desirable solution. Drought is one of the ...
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IntroductionToday, in order to prevent the destruction of water, soil and environment resources, and at the same time to achieve the desired performance in agriculture, in the conditions of environmental tensions such as drought, the use of biofertilizers is a desirable solution. Drought is one of the most important non-living environmental stresses and a limiting factor in agricultural production, especially in arid and semi-arid regions around the world. Trichoderma isolates are stimulated by various mechanisms such as competition for food and the growing environment, stimulation of plant resistance mechanisms, stimulation of plant growth and development, change of environmental conditions, especially rhizosphere and increase the solubility of mineral elements to be absorbed by the plant. Experiments have shown that the use of Trichoderma Harzianum during the basil basil can increase the number of leaves, weight and dryness, nitrogen levels and plant phosphorus relative to the control (Tallapragada 2013). Due to the increasing reduction of water resources and the confrontation of plants with water stress and reduction of quality and quantity of agricultural products in this study, the effect of different concentrations of Trichoderma Harzianum on basil plant in drought stress on morphological, biochemical characteristics and adsorption of elements was investigated. Materials and methodsAn experiment was conducted in a completely randomized design with three replications in 2018 in the greenhouse. The treatments included 3 levels of drought stress (50, 75 and 100% field capacity) as the first factor and inoculation with Trichoderma fungus (concentration 108) and non-inoculation with Trichoderma fungus as the second factor. Sampling was performed 60 days after drought stress, coinciding with the development of flowering plants. Morphological traits including wet and dry weight of aerial limbs and roots were weighed. The length of the stem and root was measured by a ruler and the leaf surface by a device measuring the surface of the leaf gauge. The total amount of nitrogen was measured by the kjeldahl method device, the amount of phosphorus was measured using a colorimeter by a spectrophotometer, and the amount of potassium was measured by a film photometer. Data analysis was performed using minitab 18 statistical software and comparison of means based on Bonferroni test at 5% probability level (p <0.05). The charts were also drawn using EXCEL software. Results and discussionThe results showed that the use of Trichoderma harzianum in different levels of drought stress had a significant effect on growth traits and adsorption of elements in basil. The highest fresh and dry weights of shoot and root organs, relative leaf water content and leaf area were observed in the treatment of 100% irrigation capacity along with the use of Trichoderma fungus with a concentration of 108 spore. Also, the highest adsorption of phosphorus, potassium and nitrogen was observed in the treatment of irrigation level of 100% field capacity with the use of Trichoderma fungus with a concentration of 108. ConclusionThe use of Trichoderma harzianum in stressful conditions in basil has improved the growth properties and increased the absorption of phosphorus, potassium and nitrogen in the plant. In general, in this study, the highest increase in the observed trait was observed in the treatment of irrigation level of 100% field capacity with the use of Trichoderma fungus with a concentration of 108.
Drought stress
Shokofeh Gholami; Majid Amini Dehaghi; Ali Reza Rezazadeh
Abstract
IntroductionDrought stress is a major constraint to agricultural productivity all around the world. Drought is the most significant threat to global food security. Food demand becomes a huge issue because water supply is restricted around the planet. Plant seed priming is a simple, low-cost, low-risk, ...
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IntroductionDrought stress is a major constraint to agricultural productivity all around the world. Drought is the most significant threat to global food security. Food demand becomes a huge issue because water supply is restricted around the planet. Plant seed priming is a simple, low-cost, low-risk, and effective way to boost plant tolerance under stressful situations.In nutrient priming, seeds are pretreated (primed) in solutions containing the limiting nutrients instead of being soaked just in water. Microelements, which are required in very small quantities, play important roles in improving crop productivity and quality. Oxidative stress is caused by the formation of active oxygen species (ROS) in response to water stress. Antioxidant enzymes are regarded to be the "first line of defense" against reactive oxygen species (ROS) produced by a variety of environmental injury species. Selenium's strategies for decreasing the effects of drought are mostly anti-antioxidant defense activation. Quinoa (Chenopodium quinoa Willd) is a stress-tolerant pseudo cereal that has been cultivated for over 7000 years in the Andes, in a variety of environments, with Peru and Bolivia being the main producers. Quinoa is a high-protein food (12-16.5 percent), with protein quality comparable to casein. Furthermore, this "wonder grain" is gluten-free and high in bioactive substances such as antioxidants, polyphenols, flavonoids, vitamins, and minerals that imparts various health benefiting characteristics to this grain. Quinoa plants, including seeds and leaves, can be eaten to provide nutrition to humans and animals. Quinoa is also great for digestion because it has twice the amount of nutritional fibre as other cereals. Materials and MethodsThus a factorial experiment in a completely randomised design with three replications was conducted in the Seed Technology Laboratory, Faculty of Agricultural Sciences, Shahed University in 2020 to investigate the effect of sodium selenite pre-treatment on germination indices and prolin content of quinoa plants under drought stress. The variables in the experiment Include four levels of sodium selenite (0.5, 1.5, 3, 4.5, and 6 mg/lit), two levels of hydroprimind and no priming, and three levels of drought stress induced by polyethylene glycol (0.4, 0.8, and 1.2 MP). Germination percentage (GP), mean germination time (MGT), germination speed (GR), and SVI: seedling longitudinal index, seedling length, changes in the number of photosynthetic pigments, and proline content, and Catalase enzyme levels were among the traits that were assessed. Statistical analysis of the data included analysis of variance using AS 9.1 software and comparison of the mean of traits evaluated by LSD test at 5% probability level. ResultsThe results showed that prime with selenium and drought stress had a significant effect on most germination traits and photosynthetic pigments, proline levels and catalase enzyme. Prime with selenium at its proper concentration led to the early emergence of seedlings in drought-tolerant conditions, but showed an inhibitory effect by increasing the concentration of selenium and increasing the levels of drought stress. Pre-treatment with selenium at 30 mg / L showed the highest percentage of germination (94%) with a 58% increase compared to non-priming and severe stress treatment. Also, seedlings that were primed with selenium had more photosynthetic pigments than non-priming and hydrophilicity under stress. The highest levels of proline and catalase were observed in extreme stress conditions with molar concentrations of 1.5 and 1.5 mg/lit, respectively. As a result, seed priming with selenium can be used to boost quinoa seedling germination and early growth under field circumstances.
Salinity stress
Masoumeh Salehi; Farhad Dehghany; Vali Soltani Gerdfaramarzi; Nadiya Besharat
Abstract
Introduction Quinoa is an allotraploid crop, C3 (2n = 4x = 36) from the Amaranthaceae family and is of great global interest due to its high nutritional value. Quinoa is native to South America and has been cultivated in these areas for 5,000 years. Quinoa has an average of 16% protein and free gluten. ...
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Introduction Quinoa is an allotraploid crop, C3 (2n = 4x = 36) from the Amaranthaceae family and is of great global interest due to its high nutritional value. Quinoa is native to South America and has been cultivated in these areas for 5,000 years. Quinoa has an average of 16% protein and free gluten. Climate change and salinity and drought stress have led farmers to turn to new plants to maintain production in these conditions. Quinoa has a high genetic diversity in terms of tolerance to salinity stress, maturity time and other agricultural traits. The project aims to select promising quinoa lines in saline conditions in spring cultivation. Materials and methods In order to select quinoa lines in spring cropping under saline conditions, 13 lines with different maturity periods in 3 lines with 5 meter lines at Sadough salinity research farm of Yazd based on complete randomized block design with three repetitions with 14 dS/m saline water in 2016. Initially, the seeds were planted in a seedling tray and after 21 days, transferred to the farm on March 9. Twice spraying was performed to control the spodoptera larvae during the floral initiation stage. The three stages of urea fertilizer were carried out at first, at the beginning of the floral initiation and anthesis stages. The phenological steps were recorded and the sodium percent, the potassium percent in the leaves and the ratio of potassium to sodium in the anthesis stage and finally the plant height, the thousand kernel weight (TKW), biomass and seed yield were measured. Data were analyzed with SAS software and cluster analysis, correlation analysis and principle component analysis were performed by Statographic software. Results and discussion The results of analysis of variance showed that in terms of all the measured traits the difference among the lines was significant. The mean comparison showed that Line 6 had the highest seed yield (1422 Kg ha-1) with a significant difference, and then Lines 7, 10 and 11 had high seed yield. TKW of lines 6 and 11 with a rate of 1.9 and 1.8 g had a significant difference with other lines. The correlation relationship between traits showed that seed yield had significant correlation with TKW and days to maturity. In the cluster analysis, lines 11 and 6 in the early group had the highest seed yield and TKW. The high temperature during the period of grain filling in spring cultivation reduced the seed yield and TKW and lines 15 and 16 because of high temperature and long day did not start flowering. The evaluation of temperature in the grain filling period showed that with increasing each degree of the average temperature and maximum temperature seed yield decreased by 118 and 184 Kg ha-1 and TKW decreased by 0.2 and 0.27 g, respectively. Principle component analysis showed that the three components had the largest share in variance, and in the first, second and third components, the TKW, the ratio of potassium to sodium and the percentage of potassium in the positive direction and day to maturity, day flowering and plant height with seed yield had the largest share in the negative direction, respectively. Lines 11, 6 and 10 had the highest share in the total of three components in the direction of yield. Conclusions Quinoa had a high ability to absorb potassium under salinity stress, and the heat of the end of the season reduced the yield and TKW in the late mature genotypes. The most important traits for selection in spring cropping under salinity stress were grain yield, early maturity, TKW and potassium-to-sodium discrimination trait, and finally lines 11 and 6 were selected for further study in spring cropping. Among the studied traits, TKW, day to maturity, and the percentage of sodium and potassium ions were effective in line selection.
Salinity stress
Zahra Nasiri; Jafar Nabati; Ahmad Nezami; Mohammad Kafi
Abstract
IntroductionChickpea (Cicer arietinum L.) is one of the important legume crops and Globally, after beans )Phaseolus spp(., chickpea is ranked as a second important legume crop (Roy et al., 2010). Chickpea is an important source of proteins for human consumption, especially in the developing countries ...
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IntroductionChickpea (Cicer arietinum L.) is one of the important legume crops and Globally, after beans )Phaseolus spp(., chickpea is ranked as a second important legume crop (Roy et al., 2010). Chickpea is an important source of proteins for human consumption, especially in the developing countries where people cannot provide animal protein or vegetarian by choice (Zaccardelli et al., 2013). Chickpea plays an important role in the maintenance of soil fertility through nitrogen fixation (Roy et al., 2010). Plants are exposed to wide range of environmental stresses. In among, Salinity is one of the major abiotic stresses causing severe impact on crop production worldwide(Rasool et al., 2012).chickpea is a salt sensitive pulse crop and its yield is seriously affected mainly by salts (Turner et al., 2013). Salinity stress in chickpea adversely affects several morphological features and physiological processes like reduction in growth and ion balance, water status, photosynthesis, increase in hydrogen peroxide, which causes lipid per oxidation and consequently membrane injury. Also proline and carbohydrates are accumulated in plant tissue (Flowers et al., 2010; Ashraf and Harris, 2004). This study is designed to determine the effect of salt stress on physiological and biochemical parameters in chickpea genotypes exhibiting differences in salinity tolerance. The results of this study could provide information on potential physiological and biochemical parameters and could also provide deeper intelligence into tolerance mechanisms than the stresses caused by salinity.Materials and methodsThis experiment was conducted as split-plot based on randomized complete block design with three replications in 2018 at Ferdowsi University of Mashhad, Mashhad, Iran. Salinity with two levels of 0.5 and 8 dSm-1 (NaCl) was considered as main plot and chickpea genotype (17 Kabuli-type genotypes) as sub-plot. The characteristics such as soluble carbohydrates, proline, osmotic potential, MDA, DPPH, relative water content, MSI%, were evaluated in 50% of flowering. At the end of the growing season, crop was harvested and seed yield were determined.Results and discussionThe highest proline and carbohydrates content was observed in MCC65, MCC92 and MCC95 genotypes, and the lowest in MCC12 genotype. Result salinity stress caused increased 24, 19 and 19 % in the amount of osmotic potential, MDA and DPPH. Relative leaf water content and membrane stability was showen respectively 10 and 13 % reduction by use salinity stress. Survival percentage, number of branches and canopy height had reduction 6, 22 and 57. MCC65, MCC92 and MCC95 genotypes respectively by 0.183, 0.193 and 0.181 (Kg.m-2) had the highest seed yield and MCC98 and MCC298 had the lowest seed yield. The MCC65, MCC95 and MCC92 genotypes had superior traits, including performance in stress conditions compared to other genotypes, and on the other hand, the MCC98 and MCC298 genotypes had the lowest performance. Among 17 chickpea genotypes, the highest sodium content belonged to MCC95 genotype with 9.5 (mg.g.dw-1) weight and the lowest sodium MCC65 genotype with 5.8 (mg.g-1dw). MCC65 had the highest potassium in non-stress and MCC95 had the highest potassium in salinity stress.ConclusionsThe MCC65, MCC95 and MCC92 genotypes had superior traits, including performance in stress conditions compared to other genotypes, and on the other hand, the MCC98 and MCC298 genotypes had the lowest performance. Finally, further study in relation to the top three genotypes in salinity stress conditions is proposed to identify stress tolerance mechanisms as well as infrastructure as breeding programs.
Salinity stress
Gholamhassan Ranjbar; Hadi Pirasteh-Anosheh; Mehdi Shiran Tafti; Majid Nikkhah
Abstract
IntroductionIn regions with severe limitation of fresh water, salinity poses a serious threat to agriculture production due to its toxicity to most plants. Salinity tolerant plants that can survive and grow in high-salinity conditions are called halophytes. Halophyte cultivation has the potential to ...
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IntroductionIn regions with severe limitation of fresh water, salinity poses a serious threat to agriculture production due to its toxicity to most plants. Salinity tolerant plants that can survive and grow in high-salinity conditions are called halophytes. Halophyte cultivation has the potential to restore saline environments, provide for global food demands, produce medicine and biofuels, and conserve fresh water. Two approaches are presented to developing tolerant plants of seawater salinity; the first is increasing tolerance of conventional plants, and the second is choice from the large pool of halophytes, which already have the requisite salt tolerance. The difference between the upper limit of salt tolerance of conventional plants and required tolerance level to seawater salinity is huge. It has been shown that Salicornia spp. has the potential to tolerate salinity of seawater. Salicornia is a genus of succulent, halophyte flowering plants in the family Amaranthaceae that grow in salt marshes, on beaches, and among mangroves. Pickleweed (Salicornia bigelovii Torr.) is an obligate halophyte that has been considered as a promising plant due to the tolerance to hypersaline water and economic values such as forage production, oilseed production and fresh consumption. This study evaluated the response of Salicornia bigelovii to different water salinity treatments, determines its salt tolerance threshold and shows trend of the accumulation of Ca2+, Cl-, Na+ and K+ ions in the plant shoots. Materials and methods This experiment was conducted as a completely randomized design with 4 replicates in the greenhouse of the National Salinity Research Center, Yazd, Iran. Saline water treatments included 2, 5, 8, 11, 14 and 17 dS m-1, which were prepared using dilution of Persian Gulf water. Salinity treatments were applied as irrigation of pickleweed (Salicornia bigelovii) plants with related saline water treatments. The 10 uniform seeds were sown in pots and were kept in a controlled environment with 26/18 °C (±3) day/night temperature regimes. The 84 days plants were harvested and were immediately transferred to the laboratory. Fresh and dry weight, dry matter, ash content and concentration of calcium (Ca2+), chloride (Cl-), sodium (Na+) and potassium (K+) were measured in shoots. Data were subjected to analysis of variance, and the means were compared using LSD at 5% probability level. Response cure was used to determine the threshold level of reduction after reaching the peak.Results and discussionThe results showed that salinity treatment was significant on all traits, except dry matter percent and potassium concentration. The results showed that increasing salinity up to 8 dS m-1 increased fresh and dry weight, however higher salinity levels were associated with reduction. The threshold level of reduction after reaching to the peak were 8.65 and 7.01 dS m-1 for fresh and dry weight, respectively. The amounts of reduction in fresh weight in 2, 5, 11, 14 and 17 dS m-1 treatments compared to 8 dS m-1 treatment were 26.9%, 9.5%, 12.0%, 20.0% and 35.8%, respectively. These reductions were 23.4%, 20.7%, 27.4%, 38.9% and 41.7%, respectively in dry weight. With increasing salinity of water, the ash content of shoots had an ascending and significant trend. The lowest and the highest shoot ash were related to 2 and 17 dS m-1 water salinity, by 24.8% and 41.3%, respectively. As salinity was increased, the concentration of chlorine and sodium in shoots were enhanced, while the concentration of calcium and potassium were reduced. Correlation and stepwise regression analyses revealed that concentration of calcium and potassium were the most important traits in salinity tolerance of salicornia. It seems that salinity tolerance in salicornia occurs by osmotic regulation as the accumulation of salts in its tissue.ConclusionsAccording to the results of this study, it can be concluded that the capability of ions accumulation strengthens the phytoremediation ability of salicornia, however increasing in ash content could have a negative effect on the forage value of the plant. Therefore, determining the nutritional value of salicornia and feed analyzing in the presence of livestock require further evaluation.
Salinity stress
Mohammad Hossein Banakar; Hamzeh Amiri; Gholam Hassan Ranjbar; Mohammad Reza Sarafraz Ardakani
Abstract
IntroductionIran, the second largest country in the Middle East, has an area of 165 million ha. Approximately, 90% of the country is classified as arid and semi-arid region, most of which is faced with low rainfall, high evapotranspiration, salinization, shortage of fresh water, erosion, excessive heat ...
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IntroductionIran, the second largest country in the Middle East, has an area of 165 million ha. Approximately, 90% of the country is classified as arid and semi-arid region, most of which is faced with low rainfall, high evapotranspiration, salinization, shortage of fresh water, erosion, excessive heat and desertification. Fresh water resources are declining in the central plateau of the country as a result of overusing underground water and severe drought in recent years. Land salinization is a major limiting factor for conventional crop production in the country. Continuous cropping together with an excessive use of chemical fertilizers and ill-managed irrigation has turned hundreds of cultivated fertile fields into saline ones. These limitations have great impacts on the welfare of the farmers whose income is solely dependent to agriculture. Regarding the increasing trend in the salinity of soil and water resources, cultivation of salt tolerant medicinal plants has been suggested as one of the strategy for utilizing saline soil and water resources. One of the medicinal plants that has a long history of use in traditional medicine and has also many therapeutic properties is fenugreek (Trigonella foenum-graecum L.). This research was conducted to determine the salt tolerance threshold, yield reduction slope and to evaluate effects of utilizing saline water on yield (shoot dry weight) at vegetative stage under greenhouse conditions. Materials and methodsIn this experiment, treatments were included seven levels of salinity (0.5, 2, 4, 6, 8, 10 and 12 dS/m) obtained by mixing a saline groundwater resource (with electrical conductivity of 14 dS/m) and a fresh water resources (tap water). A leaching fraction of 30% was considered to wash out some excess salts from soil profile and preventing their accumulation in the root zone. In order to control soil salinity, the amount and electrical conductivity of both irrigation and drainage water was measured in all irrigation practices. Furthermore, athe soil salinity was monitored using a soil salinity bridge instrument. The statistical design was arranged as a complete randomized block design with three replications. In this study, different experimental models were used to determine the salt tolerance threshold, the slope of yield (shoot dry weight) reduction, the amount of salinity at which yield was reduced by 50% (EC50) and the salt tolerance index, as well. Results and discussion Results showed that there was a statistically significant difference among different salinity levels. Based on the results, salinity reduced shoot height (27.66%), number of leaves (18.03%), number of branches (5.14%), number of nodes (8.77%), stem diameter (27.04%), internodes length (54.21%), mean of expanded leaves area (46.91%), root to shoot ratio (16.97%), water content (14.62%), water use efficiency (14.70%) and increased leaf thickness (73.55%) and greenness index (47.58%), however, salinity had no significant effect on special leaf area. Although salinity stress had an adverse effect on most studied traits, the trend of this effect was varied depending on the trait. Based on the linear model, the salt tolerance threshold of fenugreek and the slope of yield reduction was estimated 1.28 dS/m and 4.91 percent, respectively. However, according to non-linear models, a reduction of 10 and 25 percent in relative grain yield was occurred at 3.38 and 6.28 dS/m, respectively. Based on the results of this research, the salinity at which the relative yield decreased by 50% percent was observed at soil salinity of 11.67 dS/m. Conclusions In this research, the fenugreek salt tolerance index was calculated as 12.24. Therefore, based on both the salinity tolerance threshold, the slope of yield reduction and salinity tolerance index, fenugreek can be classified into the group of moderately sensitive to salinity stress at the vegetative growth stage.
Salinity stress
Farhad Dehghani; Parisa Malaki; Masomeh Salehi; Saeed Saadat; Hossein Ali Bahrami
Abstract
IntroductionQuinoa (Chenopodium quinoa Willd.) is a facultative halophyte with very high adaptability to varied climatic conditions and high nutritional value. Different quinoa cultivars can have economical and stable yield in saline soil and water conditions. In addition to salinity, the chemical composition ...
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IntroductionQuinoa (Chenopodium quinoa Willd.) is a facultative halophyte with very high adaptability to varied climatic conditions and high nutritional value. Different quinoa cultivars can have economical and stable yield in saline soil and water conditions. In addition to salinity, the chemical composition of irrigation water and thus soil solution affect the uptake and transfer of water and nutrients, and so plant yield. The intensity of this effect depends on various factors such as plant species. Calcium to magnesium ratio (Ca/Mg) is one of the quality indicators of irrigation water that can affect soil physical conditions and nutrient uptake independent of salinity level. A Ca/Mg < 1 and exchangeable magnesium percentage more than 25% in irrigation water are considered high enough to reduce soil quality and crop yields. Currently, frequent droughts and high water extraction have caused a sharp drop in water levels, increase in salinity, and in some cases a decrease in the Ca/Mg in the groundwater of most arid regions of the country. Since the effect of Ca/Mg in irrigation water on growth and yield of quinoa has not been studied so far, so the aim of this study was to investigate the effect of different Ca/Mg in irrigation water on growth parameters and quinoa grain yield in saline conditions. Materials and methodsTo study the effect of different Ca/Mg of irrigation water on quinoa growth and yield, three separate experiments in a randomized complete block design with four replications were conducted at the Research Greenhouse of Soil and Water Research Institute in 2018. Experimental treatments included three different Ca/Mg in irrigation water consisting of 0.25, 0.5 and 1, which were made by sodium chloride, magnesium and calcium as nutrient solutions fit to the salinity tolerance threshold of quinoa at different growth stages. In the previous research, yield reduction thresholds for Titicaca cultivar at different growth stages in a soilless culture (perlite) were a: 8 dS m-1 for emergence, b: 15 dS m-1 for flowering and c: 20 dS m-1 for grain filling. To conduct this research, 100 quinoa seeds were planted in pots, and the pots were irrigated with 8 dS m-1 water along with the desired Ca/Mg treatments. After establishing the quinoa seedlings and thinning to six plants per pot, pot irrigation was done with 15 dS m-1 salinity along with the desired treatments. After ensuring the end of the flowering stage, the remaining pots were irrigated with 20 dS m-1 salinity with the desired treatments until physiological ripening. Finally, the analysis of variance of the data was performed using SAS software and the means were compared with the protected LSD at 5% probability level. Results and discussionThe results showed that the emergence percentage and non-uniformity of quinoa were not affected by Ca/Mg of irrigation water, however, increasing the magnesium amount significantly improved the emergence rate of quinoa seeds. Although the results showed that the fresh and dry weight at the flowering stage was significantly affected by Ca/Mg of irrigation water, the yield and yield components were not significantly affected. Therefore, the quinoa growth and yield are not affected by the ionic composition of irrigation water in terms of low Ca/Mg, however, the composition of absorbed and accumulated ions in plant tissues are significantly changed. So, compared to other conventional crops, quinoa has the potential to produce economic yield in saline conditions and is not affected by the Ca/Mg of water sources. ConclusionThe results of this study showed that different Ca/Mg in irrigation water do not reduce the growth and yield of quinoa. Therefore, if the salinity tolerance threshold of the plant is considered, low water quality in terms of high magnesium concentration does not damage the plant and so can be cultivated with saline water sources such as diluted seawater.
Salinity stress
Atefeh Rashidifard; Mostafa Chorom; Mojtaba Norozi Masir; Habibolah Roshanfekr
Abstract
IntroductionSoil salinity is one of the most serious abiotic stress factors limiting crop productivity. Salinity disrupts plant morpho-physiological processes because it causes an increase in reactive oxygen species (ROS). One of the relatively new methods to increase the plant yield and reduce oxidative ...
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IntroductionSoil salinity is one of the most serious abiotic stress factors limiting crop productivity. Salinity disrupts plant morpho-physiological processes because it causes an increase in reactive oxygen species (ROS). One of the relatively new methods to increase the plant yield and reduce oxidative stress under salinity stress is seed- pretreatment or priming. Recently, compounds containing zinc as well as humic substances have been widely used to improve the quality and quantity of agricultural products. This study investigates the potential of seed priming by humic acid and zinc as the methods to overcome on limitations of seedling growth affected by soil salinity stress. Materials and methodsAn experiment was conducted as split plot using a randomized complete block design with three replications at 2019 in the research greenhouse of the Faculty of Agriculture, Shahid Chamran University of Ahvaz, Iran. Experimental treatments were included soil salinity (at two levels included non-saline and saline soils with an electrical conductivity of 2.2 and 8 dS m-1, respectively) as the main factor and seed-pretreatment (at 4 levels included 250 mg l-1 solution of humic acid [HA], 4 mM zinc sulfate [Zn], 250 mg l-1 humic acid + 4 mM zinc sulfate [HA+Zn] and non-primed seed as control [Co]) as sub-factor. The maize seeds were disinfected and then pre-treatment was carried out in such a way that the seeds were exposed to the desired treatments (HA, Zn, HA + Zn and Co) for 24 hours in dark room at 15 ˚C. After the soaking of the seeds with the solutions, 10 maize seeds were sown in both saline and non-saline soils and cultivation was done in plastic pots and after reaching the 3-4 leaf stage, the density in each pot was reduced to 4 plants. In the sixth week at the start time of corn silk (stop the root growth), all the plants were harvested and some vegetative, physiological and biochemical traits were measured and analyzed. Results and discussionThe analysis variance of salinity and seed pre-treatment effects on the some morpho-physiological traits of corn seedlings showed that salinity stress has significantly reduced the length of shoot and dry weight of the shoot and root, amount of chlorophylls a and b and the values of leaf area and increased the activities content of catalase and superoxide dismutase enzymes, as well as the amount of proline compared to seedlings grown in non-saline soil so that the amount of length of shoot, dry weight shoot and root, leaf area, chlorophyll a and b were reduced 42.6, 38.9, 55.9, 33.9, 51.7 and 48.1%, respectively due to salinity, and the activities of catalase and superoxide dismutase enzymes were increased from 0.037 and 19.66 to 0.14, 30.54 U.mg-1 protein, respectively and proline value was increased from 0.356 to 1.39 mg g-1 FW. However, the priming of corn seeds significantly improved the morpho-physiological traits of seedlings in both saline and non-saline soils, so that the amount of dry root weight, which was significantly reduced due to salinity (55.9%), increased 38.1, 33.1 and 71.1% affected by priming with HA, Zn and HA+Zn treatments (compared to un-primed seeds in saline soil), respectively. It was also observed an incensement of 49.7, 44.1 and 68.6% for shoot length, 23.4, 5 and 51% for dry weight of shoot, 33.37, 29.21, and 46.4% for leaf area, 87.16, 60.36, and 101% for chlorophyll a, 45.89, 20.54 and 64.83% for chlorophyll b due to HA, Zn and HA+Zn treatments, respectively, in saline soils. Also, priming increased the amounts of antioxidant enzymes as well as proline in both saline and non-saline soils, significantly.
Drought stress
Ahmad Zare; Maede Malekpoor- Sharahki
Abstract
IntroductionKnowledge on germination ecology of weeds in response to salinity and drought stresses can help to predict weeds population dynamics in the future. Among the family of weeds, the weeds of Brassicaceae family include many important species that contaminate crops and orchards. In addition to ...
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IntroductionKnowledge on germination ecology of weeds in response to salinity and drought stresses can help to predict weeds population dynamics in the future. Among the family of weeds, the weeds of Brassicaceae family include many important species that contaminate crops and orchards. In addition to the presence of weeds, salinity and drought are also considered as limiting factors in agricultural production. Due to the increase in salinity and drought stresses in agricultural fields, it can be significant expansion and contamination of Brassicaceae weeds, because Physiological dormancy, abundant seed production and emergence at different time, leads to be persistent for long-term in soil. Therefore, the aim of this research was to compare the characteristics of seed germination of four weeds Brassicaceae family to salinity and drought stresses.Materials and methodsIn order to investigate the effects of salinity (0, 50, 100, 150, 200, 250, 300, 350 and 400 Mm) and drought stress (0, -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa) on seed germination four Brassicaceae family weeds (Rocket (Eruca sativa), Hoary Mustard (Hirschfeldia incana), Wild Mustard (Sinapis arvensis) and Treacle Mustard (Erysimum repandum), two experiments as factorial based on completely randomized design (CRD) were conducted at agricultural sciences and natural resources university of Khuzestan in 2019 with three replications. Optimum Temperature for germination were selected 25°C for Rocket, Hoary Mustard, Wild Mustard and 15°C for Treacle Mustard. Duration of test for two experiments was considered 15 days. Criterion for germination was length radicle 2-3 mm.Results and discussionBy increasing drought stress, germination, vigour index and germination rate were decreased and no germination was observed in drought stress of -1.2 MPa. 50% reduction for germination in four weeds Rocket, Hoary Mustard, Wild Mustard and Treacle Mustard were estimated in -1, -0.49, -0.76 and – 0.41 MPa of drought stress respectively. Drought stress required to reduce 50% of germination rate for Rocket, Hoary Mustard, Wild Mustard and Treacle Mustard were estimated -0.85, -0.35, -0.28 and 0.22 MPa respectively.The vigour index of Wild Mustard in conditions without drought stress treatment was more than other weeds. Rocket and Hoary Mustard were introduced as resistant and Wild Mustard was introduced as sensitive to salinity. The salinity required to reduce 50% of germination for Rocket, Hoary Mustard, Wild Mustard and Treacle Mustard were predicted 267, 162, 39 and 46 mM, while 50% reduction for germination rate were 174, 142, 27, 44 Mm respectively. By increasing salinity and drought stresses, mean germination time was increased and maximum mean germination time belonged to Treacle Mustard and the reason for this increase was the lag phase of germination. Germination rate in four weeds was more affected by salinity and drought stresses than germination percentage. Generally the germination rate of Treacle Mustard was much less than other weeds. So that the maximum germination rate of Treacle Mustard was 5 seed/day in control treatment while in Rocket Hoary Mustard, Wild Mustard were more than 30 seed /day.ConclusionsAccording to the results, in saline lands, the spread of two weeds Rocket and Hoary Mustard is more expected and in the conditions of drought stress and in rainfed agriculture, presence of Rocket is more evident than Wild Mustard.
Heat stress
Sabrieh Seimrizade; Ali Moshatati; Abd-AlMahdi Bakhshandeh; Aydin Khodaei Joghan; Ahmad Koochekzadeh
Abstract
IntroductionTerminal heat stress in Khuzestan province, decrease growth, yield and yield components of wheat. The vermicompost fertilizer improve water reserve and physical and chemical properties of soil. One of the important ways to reduce the negative effect of terminal heat stress on plant is using ...
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IntroductionTerminal heat stress in Khuzestan province, decrease growth, yield and yield components of wheat. The vermicompost fertilizer improve water reserve and physical and chemical properties of soil. One of the important ways to reduce the negative effect of terminal heat stress on plant is using vermicompost fertilizer in the soil. Using vermicompost fertilizer in agricultural soils lead to increase nutrient elements and conserving the soil water and decrease the negative impacts of drought stress on plant. Generally, vermicompost fertilizer contribute to preserving the moisture storage of the soil and to supply the nutrients required by the plant. In this study, the most important aim is to study the effect of vermicompost fertilizer on bread wheat yield and yield components under terminal heat stress in Ahwaz climatic condition. Materials and methodsIn order to evaluate the effect of vermicompost fertilizer on growth and yield of wheat in terminal heat stress of Ahwaz, a field experiment using split-plot design based on randomized complete block design with four replicates was conducted in research farm of Agricultural Sciences and Natural Resources University of Khuzestan during (in 31º N, 48º E, 35 Km north-east of Ahwaz, and 20 m above the sea level) 2017-2018 growing season. Experimental factors were three sowing dates (22 Nov., 11 Dec. and 31 Dec.) in main plots and five vermicompost rates (0 (control), 5, 10, 15 and 20 t.ha-1) in sub plots. Results and discussionAnalysis of variance showed that the effect of sowing date and vermicompost were significant on measured traits. Mean comparison revealed that the highest grain yield (2356 kg.h-1) was at the first sowing date and the lowest grain yield (1732 kg.h-1) was at the last sowing date. Also, in vermicompost levels, the maximum grain yield (2593 kg.ha-1) was in 20 t.ha-1 of vermicompost application and the minimum grain yield (1566 kg.ha-1) was in control of vermicompost. ConclusionsGenerally, the results showed that with delay in sowing date and occurrence of terminal heat stress, decreased growth and grain yield of wheat. But, using vermicompost fertilizer decreased the negative impact of drought stress. So that, with increase vermicompost application, increased measured traits. Also, in areas with terminal heat stress after flowering stage, using 20 tons per hectare of vermicompost fertilizer is recommended for maintaining grain yield.
Heavy metals
Zahra Vatanpour; Rouhollah Motafakker Azad; Soodabe Jahanbakhsh; Ali Movafeghi; Mohsen Sabzie Nojah Deh
Abstract
IntroductionHeavy metal pollution is one of the major problems of human societies in the production of agricultural products and is considered as a major threat to human health. Wheat is a strategic crop in human nutrition and the growing global population requires more agricultural production. To achieve ...
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IntroductionHeavy metal pollution is one of the major problems of human societies in the production of agricultural products and is considered as a major threat to human health. Wheat is a strategic crop in human nutrition and the growing global population requires more agricultural production. To achieve high yields of crops, especially in developing countries, chemical fertilizers and pesticides are widely used, which causes excessive accumulation of heavy metals in agricultural soils and has detrimental effects on human health and other living organisms. Increasing the concentration of heavy metals in the soil on the other hand affects the toxicity and growth and yield of crops. Considering the mentioned cases and the importance of wheat as a major human food, the present study aimed to investigate the effect of plant growth-promoting rhizobacteria (GPR) in reducing the effects of cadmium in two wheat cultivars and their effect on plant pigments. It was done by examining the change in the content of plant pigments. Materials and methodsThe experiment was carried out as a factorial experiment in a completely randomized design with three replications in Research Greenhouse of Agricultural Faculty of Mohaghegh Ardabili University in 2018. Experimental treatments included cadmium chloride stress (CdCl2H2O 0, 75, 150 and 300 μM) and the effect of growth promoting bacteria (Azotobacter and Pseudomonas). The studied traits included content of photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophyll and chlorophyll a/b ratio), adjuvant pigments (carotenoids, flavonoids), quantum yield, SPAD, stem dry weight, yield, seed weight and number of seeds. Results and discussionsThe results of analysis of variance of the main photosynthetic pigments (chlorophyll a, chlorophyll b and total chlorophyll) at 24, 48 and 72 hours after cadmium treatment and shoot showed that the interactions of the cultivar in bacteria at 72 hours on chlorophyll a (5% level) and was significant on chlorophyll b and total chlorophyll (1% level) . Comparison of means showed that the highest amount of chlorophyll b (without change compared to control) and total chlorophyll (4.63% compared to control) of Karim and chlorophyll a (95.3% compared to control) in Gonbad cultivar in the range 72 hours were observed. The highest amount of chlorophyll a was 6.31 mg / g and total chlorophyll (7 mg / g) was observed from Gonbad cultivar and inoculation with Azotobacter, which was not significantly different from the control. In the case of chlorophyll b, the lowest amount (0.57 mg / g) was obtained from the use of Pseudomonas in Gonbad cultivar and bacterial inoculation in Karim cultivar had no significant effect. The superiority of Karim cultivar over Gonbad cultivar is probably due to the genetically precocious of Karim cultivar and faster maturation process. In addition, different wheat cultivars have significant differences in cadmium accumulation in their organs because plants absorb more cadmium in stress conditions by secreting siderophore to compensate for nutrient deficiencies. Gonbad cultivar is probably more sensitive due to the absorption of heavy metals, which in turn produces more reactive oxygen, and consequently oxidative stress and degradation of photosynthetic proteins and a decrease in chlorophyll content. Among bacteria, genus pseudomonas increases plant phosphorus uptake due to its high ability to dissolve insoluble mineral phosphate. Phosphorus, as an energy carrier, increases the uptake and transport of nitrogen to the leaves, as a result in the production of higher amounts of chlorophyll. Pseudomonas may have produced more chlorophyll by increasing the uptake of trace elements by stimulating the activity of the ATPase protein pump and converting insoluble phosphate into a plant-usable form. The interaction of cultivar in bacteria was significant for carotenoids at 24 hours, flavonoids at 24, 72 and shoot stage at 1% level and for carotenoids at 72 hours and quantum yield at 48 hours at 5% level showed significance. Comparison of the mean interaction of cultivar in bacteria also showed that the highest amount of carotenoids (0.67 mg / g) was obtained in 24 hours from Gonbad cultivar and inoculation with Azotobacter, while in 72 hours of control treatment in Karim cultivar the highest carotenoids (0.61 mg / g) and did not differ significantly from Pseudomonas treatment. The decrease in carotenoids is probably due to their role in the non-photochemical suppression of excited chlorophylls, which disrupts the structure of these pigments and ultimately reduces the amount of these pigments. Cadmium appears to act as a degradation agent for pigments and other macromolecules by increasing ROS accumulation and degrading photosystem II. Non-photochemical suppression of excited chlorophylls can be another cause of degradation and reduction of auxiliary pigments. Among the main stressful effects on stem dry weight, yield, seed weight and number of seeds, the effect of cadmium on these traits (except number of seeds) was significant at the level of one percent. The interaction effect of cultivar on bacteria on stem dry weight (at 1% level) number of seeds (at 5% level) was significant and in other cases no significant. Regarding stem dry weight, Azotobacter was more effective than Pseudomonas on Karim cultivar and the number of seeds of Karim cultivar increased more in the presence of bacteria than the control. This is probably due to the higher resistance of Karim cultivar to cadmium toxicity and also due to the higher efficiency of carbon cycle enzymes in this cultivar. ConclusionsThe results showed that cadmium decreased photosynthetic pigments, increased auxiliary pigments (such as carotenoids) and decreased dry weight, yield, grain weight and number of grains in wheat plants studied. The presence of plant growth stimulating bacteria improved the photosynthetic system, dry weight, seed weight, number of seeds and yield. Application of Azotobacter growth promoting bacterium had the best results, so that in most of the studied traits, it improved the stress effects of cadmium; Therefore, Azotobacter can be used as a bacterium that reduces the stress effects of cadmium in Karim wheat.
Zohreh Bakhtiyari; Gholamreza Asghari; Shokofeh Enteshari; Rasol Soltani
Abstract
IntroductionThe traits and morphological characteristics of plants have a great impact on plant taxonomy and classification, so it is important to study these changes due to the impact of climatic factors. Climate factors can have impact on vegetative growth and the morphology of plants. One of the climatic ...
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IntroductionThe traits and morphological characteristics of plants have a great impact on plant taxonomy and classification, so it is important to study these changes due to the impact of climatic factors. Climate factors can have impact on vegetative growth and the morphology of plants. One of the climatic factors is light, which will have a different effect on plant growth and morphology, based on the amount of light intensity and plant type. Investigating the effect of light with different intensities in a plant can help determine the proper light for that plant. Our goal in this paper was investigate the effect of light with different frequencies on growth of the plant Artemisia aucheri Boiss.Artemisia aucheri Boiss. Or Artemisia is a plant that is of family Asteraceae that has a large dispersal in northern Iran. This plant has different healing properties and thus it´s necessary examining and performing various experimental activities on the plant. As mentioned, the aim of this study was to investigate the changes in growth, against different light irradiation and UV radiation on this plant thus the effect of light with different frequencies on vegetative growth of Artemisia(Artemisia aucheri Boiss.), as well as the effect of UV rays with a wavelength of 320 nm, was investigated. Materials and methodsFor culture, Murashing and Skoog solid culture was used, without growth regulators. Culture medium was under sterile conditions, the temperature of 2 ±25 and different light conditions with different treatments. Lighting conditions was used of optical radiation 1000, 2000 and 3000 lux. In addition it was assumed radiation treatments UV and treatment of darkness. This experiment was repeated several times over a period of five months, with repeated repetitions, to prevent the possibility of a possible error. Each time the experiment was repeated, with three replicates of the treatments, and in addition, the apparent variation of plant changes, fresh and dry weight of the plants harvested, recorded and compared. For analyzing data of software SPSS version 20 and Excel programs were used. During the experiment, the resulting data, the average of three replicates ± SD and results based on one-way ANOVA test, Tukey test and a significant difference on the P ≤ 0.05, were investigated. Results and discussionThe results of the effect of light on fresh and dry weeds of seedlings showed that light radiation with different intensities caused a significant difference also UV rays can affect the fresh and dry weight of the plant. According to statistical analysis results between wet and dry weights of all samples, there was a direct relationship. However, the largest amount of fresh and dry weight of the seedlings was observed in treatment 3, the irradiation of 3000 lux treatments with all treatments and control treatments showed significant differences. Morphological changes were observed by UV treatment. Changes in the apparent symptoms of the plant due to the use of radiation can be expressed as deformation and color of leaves, leaf drying, cholorosis and necrosis in leaves (decreasing chlorophyll content), increasing leaf and stem thickness, decreasing stem elongation and root. The absence of light affects the outer shape of the plant, and its longitudinal growth rate. Plants that were in an environment without light usually had long, narrow stalks. However, the stems were yellow, but much longer and thinner than other treatments. The leaves did not spread much and were yellow. The plants that grew in the dark have a formidable appearance. Their shoots were longer and their diameter was smaller and pale. Increasing fresh and dry calluses in this treatment showed a significant difference with all treatments, and the weight gain was higher than the rest, except for 3000 lux. On the other hand, the colors of the calluses were creamy to the color of the coffee, and more were slim and sticky. Some parts of the callus were purple. ConclusionOne of the most important environmental conditions affecting plant growth and how it affects is light conditions. According to the information obtained, the intensity of light irradiation increases, the growth rate and plant density are improved and the plant weight is increased. The best lighting conditions in this experiment is 300 lux, the longitudinal growth and transverse growth of the plant, the better and even on root growth the impact a lot. Ray of UV the shape plant and root growth and stem of the plant was effective. With regard to the study of the irradiation of more than 3,000 lux in this experiment, it is suggested that higher radiation for this plant should be investigated in subsequent studies.
